Arrange one layer of potatoes in the bottom of the prepared baking dish. Sprinkle the potatoes with salt, 3 tablespoons flour and 2 tablespoons butter. Repeat layering 2 more times, until all of potatoes have been used. Slowly pour milk over the potatoes until the dish is 3/4 full of milk.

3.

Bake until the milk comes to a boil (check after 5 minutes), then reduce heat to 375 degrees F (190 degrees C) for another 45 to 60 minutes.